Brooklynella (Clownfish Disease)

Dermatological and Respiratory Signs

• Hypersecretion of Mucus: The defining symptom. The fish appears as though it is sloughing a thick, white, cloudy slime coat that envelops the entire body, leading to extensive skin peeling.
• Lethargy and Anorexia: Complete loss of appetite and listless hovering near the substrate.
• Gasping and Respiratory Failure: As the thick mucus accumulates on the gill lamellae, oxygen diffusion is catastrophically blocked, resulting in suffocation.
• Hemorrhagic Lesions: Advanced stages present with deep red, raw, bleeding sores as the parasite entirely consumes the epidermal layers.

Epizootiology

1. Direct Contact: Wild-caught Clownfish and Angelfish are frequent asymptomatic carriers; introduction without quarantine almost guarantees an outbreak.
2. Stress-Induced Proliferation: High shipping stress, poor water quality, or thermal shock severely compromises the mucosal immune barrier, allowing dormant populations to explode.

Toxicological Eradication

Brooklynella does not respond reliably to copper therapy or hyposalinity.

• Formalin Baths: The definitive, scientifically proven cure for B. hostilis. A 45-to-60 minute bath in a highly aerated container using 37% formaldehyde solution (formalin) at a concentration of 250 ppm (1ml per gallon) strips the mucus layer and chemically eradicates the ciliate. This bath must be repeated every 24 to 48 hours for up to 3 treatments, transferring the fish to a sterile hospital tank afterward.
• Ruby Reef Rally (Acriflavine/Aminoacridine): An effective alternative to formalin baths, offering potent anti-protozoal properties with lower toxicity to the host.
• Chloroquine Phosphate (CP): Maintained at 15 mg/L in a hospital tank, CP serves as an excellent broad-spectrum treatment that easily penetrates the mucosal slime.

Prophylactic Husbandry

• Formalin Dips on Arrival: Many advanced aquarists and wholesalers perform routine formalin dips on all newly arrived Clownfish to instantly knock back Brooklynella.
• Fallow Tanks: The parasite requires a fish host to survive; leaving a display tank fish-less for 6 weeks will completely eradicate the population.